Final answer:
The correct answer is option a. Yvette accuses the group of having the murderer among them after revealing Monsieur Boddy's death in the given scene.
Step-by-step explanation:
The scene provided centers around a character named Yvette who makes a startling declaration to a group that there is a killer among them following the death of Monsieur Boddy. Yvette's statement "Plus, one of you is ze killer! Monsieur Boddy is dead!" can be analyzed in terms of the options provided.
Given the context, Yvette's role is to accuse the group of harboring the murderer, suggesting suspicion and tension among the characters, thus answer option (a) is the correct interpretation of the scene.